Liquid pressure system



w. c. TRAUTMAN 2,358,949

LIQUID PRESSURE SYSTEM Find April 1'7. 1941 Sept. 26, 1944.

INVENToR' 4B/glia' C. Tmui'nm.

' pipe line.

Patented Sept. 26, 1944 LIQUID PRESSURE sirs'rEM Walter C. Trautman,l4os Angeles, Calif., assignor,

by mesne assignments, to Bendix Aviation Corporation, South Bend, Ind., a corporation oi.'

Delaware Application April 17, 1941, serial No. 389,052

(cl. so52)` 4 Claims.

.I'hls invention relates to liquid pressure remote control systems, and particularly to installations where it is desirable that a choice of pipe lines should be available, such, for example, as on military aircraft where there is always a danger oi' one or more of the component parts of the system becoming inoperative.

As pointed out in Patent No. 2,186,235, issued to F. V. Brown on January 9, 1940, the pipe lines oi a remote control system are perhaps most liable to this danger as they extend usually for long distances, and are rendered inoperative by a rupture at any point in their length.

Regarded broadly, therefore, an object of the invention is to .provide in a liquid pressure remote control system comprising a main powerdriven pressure producing pump and a fluid motor connected together by one or more pipe lines, an auxiliary pipe line which from a position adjacent the main pumpv can be brought into operation in place of the pipe line or one of the pipe lines normally used, the line thus replaced being isolated from the auxiliary pipeline. The invention further provides an arrangement in which a second auxiliary pipeline connects one side of the motor with an auxiliary source oi liquid pressure whereby the motor can be actuated in one particular direction in the event of destruction of both of thenormal pipe lines as 'well as the normal source of liquid. The invention is consequently useful in conjunction with aircraft retractable landing gear, the lowering of which is eifected in whole or in part by liquid pressure.

A further object of the invention is .to provide a lliquid pressure remote control system incorporating an auxiliary pipe line to be brought into use in the Vcase of destruction of the normal source of liquid, which auxiliary pipe line extends from a hndipump having connection with an emergency source oi liquid and' feeds a motor through automatic valve arranged to prevent the pressl'lfre liquid ted through the auxiliary pipe line from escaping through the normal pipe line serving to actuate the motor 'in the 'same direction as does the liquid fed through the auxiliary Another object is to provide, in coniunction with such a hand pump and emergency reservoir,

a selector valve having selective communication with either said emergency reservoir or the normal reservoir. which supplies the main pump,

according to the setting oi the selector valve, which is shittable at will.L

.Another object of the invention is to combine` a. hand pump and selector valve in a single unit having fluid passages common to both the valve and pump, and also having mounting means common to both control handles, wherefore there is eiected asaving not only indimensions and ing specification when read with reference to component parts; and

Figs. 2 and 3 show certain of the parts oi'Flg. 1'v

in other positions.

In the system shown a double-acting motor A, comprising a cylinder Ill containing a slidably mounted'piston Il, is fed normally through Aa pair of pipe lines l2 and I3, either one of which is supplied with liquid under pressure bymeans of a mechanically driven pump P which is fed with liquid from a reservoir C through a pipe il. For determining the direction in which the motor A is actuated during normal use, a reversing valve, which may be of any convenient construction, is indicated at D, in Figure 1, and is arranged sothat the delivery from the mechanically driven pump P passing through a pipe I6 can be directed'elther to the; pipe line il for I Araising the piston Il, or to the pipe line l2 for lowering said piston. It will be seen that whichever-way the piston il is actuated, the liquid rejected from the cylinder Il passes through a vpipe i9 and is returned to the reservoir C.

. The combined hand pump and selector valve assembly includes a pair of parallel bores in a common housing, the smaller bore receiving a spool-type valve element having lands SL12,

' and 53, and the larger bore receiving the pump the lower end of passage 14.

` the undercarriage.

that if the undercarriage is raised and the pump to the piston rod 58. The housing has a third bore in which is received a valve 1I whose conical head is urged by a' springv 12 toward 'a seat at The valve liner 16 has apertures registering with passages 14 and of the pump housing, also with pipe fittings 80, 8l, 82, and 83 which receive conduits f 86, 81, 88, and 89, respectively. A non-retum valve 23 in the pipe 88 and a. similar tting 24 in the pipe I8 prevent the liquid from the pump P entering the pump 54, and vice versa.

In the installation shown in Figure 1- it is assumed that the piston H is used for controlling vthe movements of an aircraft undercarriage, and that the downward movement of said piston brings about or at least assists the lowering of It will be evident, therefore,

P -becomes inoperative, dimculty might normally be experienced in releasing the undercarriage for landing purposes. This diiiiculty can be overcome in accordance with the present invention by resort to either one of two alternative methods of supplying liquid under pressure to the motor A. The first alternative method is to leave the pump selector valve-handle in the normal position as shown in Figs. 1 and 2, and operate the hand pump to draw fluid fram the normal reservoir C, and pump it into l e 88, through the` check valve 23, and into the nor al hydraulic i system. Infthis manner the pump acts to supply the main circuit independently of the pump P.

In the event that either or both the normal reservoir C and a number of hydraulic lines have been ruptured or broken away, due to gun nre, or other causes, this would render ports 80 and 82'of the selector valve useless, since port 88 to reduce the pressure on the underside of valve 1I to a point which is less than the pressure would receive no supply of oil andport 82 would feed into broken lines. In such an emergencythat is, with the power driven hydraulic pump inoperative, the normal iiuid reservoir C torn open, and one or more of the main system hydraulic lines I8, I2, and I3 shot awayit is still possible by shifting the pump selector valve han.. die to the emergency position (Fig. 3) to pump from the small emergency reservoir 98 into the down side of the landing gear motor A, by way of line 89 and valve 25. This providesv the pilot with a third means to eil'ect a safe landing by getting his landing gear down. f

In this emergency position of the selector of the iiuid flowing in from the reservoir, and

in consequence of this pressure diilerentlal the valve 1I opens t'o permit influx of fluid to refill the pump chamber to the 'left of the piston, as the latter progresses toward the right-handlimit of its stroke. As the piston reverses, valve 51 opens under the pressure of the iluid to its left, Vand this fluid thereupon ows into the pump chamber to the right of the piston, from which location it will be pumped to the delivery line on the next cycle of operation of vthe pump. During the leftward travel of the piston the valve 1I is closed by the combined action of the fluid beneath the valve and the valve closing spring 12. 'The' valves 51 and 1I are of molded, plastic material, and their frusta-conical ends are molded to produce an angular relationship slightly less thanninety degrees, so that when they engage their respective tapered seats (whose taper presents a true ninety degree included angle) they can be wedged more firmly thereagainst; the plastic constituency of the valve noses being sufficiently deformable to otlset any angular differences, and therefore produce perfect seating. What is claimed is: 1. A iiuid pressure remote control system comprising, in combination, a double-acting iiuid pressure responsive motor, a normal source of fluid pressure including a reservoir and powerdriven pump for supplying `operating fluid to said motor, an emergency reservoir, an emergency source of operating fluid for said motor, said emergency source including a hand pump and a selector valve built into a common housing and means dependent upon the position of said selector valve for causing said hand pump to deliver fluid to said motorfrom either said iirstnamed reservoir or said emergency reservoir.

2. A fluid pressure remote control system comprising, in combination, a double-acting fluid pressure responsive motor, a normal source of fluid pressure including a reservoir and powerdriven pump for supplying operating fluid to said motoxyan emergency reservoir, an emergency valve, the path of ilow is by way of port 8I-to port 14, thence past valvesll and 56 of the pump and out to line 89 by way of vports 15and 83'.

'I'he pressure thus created in line 89 will shift automatic shuttle valve 25 to the left (compressing spring 30) and allow entry of the uid'to the right-hand chamber 'of motor A, to lower` the landing gear. l

I do not claim novelty for the automatic shuttle valve 25, per se, in view of Patent No. 2,186,235, above referred to;l but the system inv which/II employ this valve is novel in the respects pointedl out herein, and deiined in the appended claims, and this is true also of the mechanical construction of the hand-pump and selector 'valve assembly, and the mode of operation' thereof.v As ,to

the mode of operation. it will'be seen that during movement ofthe piston r'odf58 tothe right, the valve 51 will be seated and therefore the iiuid to the right Oithe PiSton will be Pumped to the'deliveryline byway of port 15 and the selector valve. Also duringthis' movement of the piston to the right, the absence of iluid to the source of operating iiuid=for said motor, said emergency source including a 4hand pump and a selector valve built into a common housing and connected to said rst named reservoir and said emergency reservoir, and means dependent upon' the position of said selector valve for causing said hand pump to deliver liluid to only one chamber of said motor, or to both chambers alternately.

3. A fluid pressure remote control system comprising, in combination, a double-acting fluid pressure-responsive motor, a normal source of liluid pressure including a iirst reservoir and pump for supplying fluid under pressure to said motor for moving the same in `either direction in eating uid from-said selector valve to said hand' pump and viceversa, a first reservoir connected to said selector valve, a power pump for delivering liquid from said rst reservoir to either side of said fluid motor; a second reservoir connected to said selector valve, and a. pair of conduits leading from said selector valve to one side of said motor through an interposed shuttle valve, said selector valve in one position. connecting said iirst reservoir to the hand pump inlet and the hand pump outlet to one of said conduits, and in another position connecting said second reserv'oir tothe hand pump inlet and the hand pump outlet to the other of said conduits.

WALTER C."I'RAUTMAN. 

